But it's a specific model, intended for the 870 Police or trench gun, with the 8-round magazine extension. Here's what one looks like, I found it on a website a while ago, but lost the site after a hard drive crash. Any of you folks know where this thing can be found?

Hope it is what you are looking for. For $19.95, Winchester, Mossberg and Remingtons-heat shields. Try:http://www.bushmaster.com
Go to "on line shopping", then go to "Shotgun Swat parts". Hope it helps.

Thanks, Ned! I know about those plain vanilla heatshields, but what I'm looking for is the model in the picture, which has the bayonet lug for the 870 Police or Trench gun, note also the long magazine tube clamp.

Gewehr 98,
I know the website that it might have been on. The item was Part #72058, and was listed as 'Mount,Bayonet'. It was available from Scattergun Technologies when Roger Small owned the outfit.
They had a large selection of versions of the Remington 870 and 11-87 shotguns available, including a military styled version called the Military Model, # 90133, which had the bayonet mount and the heatshield. FYI, the heatshield/bayonet mount combo was made for an 18" barrel (with a +2 magazine extension), so in order for the bayonet mount to work on anything longer, you would have to remove the shield, which might involve some cutting.
In 1995-96, the bayonet mount sold for $95.00 at Scattergun Tech. When I called in 1999, they had said that the bayonet mount (and the Military model 870) had been discontinued (this was the time that Bill Wilson had bought out Scattergun Tech). One of the reps gave me his fax number, but I have not used it.
I imagine that the bayonet mount was a component that was subcontracted out from Scattergun Tech because when I had called Scattergun Tech about availability in mid 1996 I was told that they were out of stock at the present time, and were expecting more in. Unfortunately, I did not follow up on this.
Remington was the original manufacturer of the bayonet mount (although it had a bead instead of a blade sight) for interested law enforcement agencies, and some might have made their way out into the civilian market, but I have never seen them and guess that Remington has not offered this item in probably 15-20 years.
The bayonet mount was actually used on the U.S Marine Corps Remington 870 Mark I shotgun (NSN 1005-01-065-8989), which had a 21" barrel, +3 magazine extension, rifle sights, walnut furniture and a parkerized finish. It was part of a family of combat shotguns that Remington created in the late 60's that had the Remington 870 and the 1100 as the base for the various models that were or were planned to be available.
The Marines received around 4000 of them, and used them during the Mayaguez incident in the 70s (I have pics), and Desert Storm (for clearing trenches and bunkers as well as on ship boarding parties, also have pics) for certain. I also know of a former Marine who carried one on sentry duty at an air station in the late 70s/early 80s. It was also used by one of the main characters in the movie "The Walking Dead", a film about a Marine Recon squad in Vietnam.
I have been looking for this component (or rather 3 of them) in order to make reproductions of the Remington 870 Mk.I, Remington 7180 Mk.I (combat version of the 1100), and a custom home defense shotgun. I kick myself every time I think about how I could have gotten them if I knew that the window for them was limited at Scattergun Tech. If you want the fax number of Small, I can offer it to you if you will share the results with me. If you want, we can form a loose knit group of persons searching for this item that eludes us (I know of two other people that expressed interest in the bayonet mount).
I can also refer you to a book that has the largest amount of information i know of available on the shotgun and the specific part. It is 'The World's Fighting Shotguns', by Tom Swearengen CWO, USMC (ret.), and printed by Ironside International Publishers originally in 1978 or '79, but I think is still available from Stackpole books. He was also doing a follow-up second edition, but passed away about 6 months ago. However, someone is continuing the work on the book.
Sorry this got so wordy, but this has been the largest obstacle for me in trying to put together reproductions of these shotguns. I have never heard of of these being taken out of inventory and sold as surplus on the civilian market, so I think that making one's own is the only route to take. And it has become a bit of a quest that absorbs me now and then. Please feel free to contact me if you want to know more, though I think you have to add the number '1' in my e-mail address in my user profile after 'maolson'.

My own 870 Police model started life as an 870 Express, then received a 20" smoothbore deer rifle with iron sights. I found a factory Remington magazine extension tube with the bayonet lug, which I thought would complete the whole picture. But now the magazine tube extension has no support from the barrel, relying solely on the mag tube's threads, and it doesn't really stay together well when lugged aropund with the sling. I need to tie the bayonet lug sleeve to the barrel somehow to prevent the mag tube rotating on it's threads, preferably by the heatshield's clamp bolts. So what I may end up doing is fabricating and parkerizing two metal strips to bolt the lower tube back to the heatshield bolts, unless there's a better alternative out there. See the picture below. I'd welcome any suggestions. And thank you for the references, although I have a feeling such things are probably long gone from Scattergun's inventory by now.

Gewehr 98,
Where did you find that bayonet mount? Are there any more available from the same source? The closest that I have come is a couple of stripped down brackets that are incorrectly drilled and missing the bayonet lug/swivel mount, and only have a bead sight.

at the Cal-Expo gun show in Sacramento about 3 years ago. It was combo mag extension tube/bayonet mount packaged in the original Remington box. On the table next to it was a metal topfolder stock, marked Law Enforcement, still in it's original factory box, too. I paid all of $39.00 for the mag tube/bayo mount that day, and should've grabbed more, I guess. So what do I do to affix this mount to the barrel for stability? Am I missing a part, perhaps another shroud for the barrel?

Gewehr, by eyeballing the pic, it looks like a standard bbl/extended mag clamp will work. Most cop shops carry them as a separate item. This will tie everything together, and....

I learned at an FBI run instructors' school that one big advantage of using an extended mag and clamp besides the more rounds is that it in effect stiffens the bbl and regulates bbl vibration, making smaller groups with slugs.
Clamping mine cut groups size nearly in half at 50 yards.

I've still reservations about needing a heat shield on a shotgun, as much as I've fired them I've never made a bbl glow red. However, it's your money,shotgun and life...

Gewehr 98,
There should be two ways that the mag tube is locked in with the Remington bayonet mount and the barrel:

1. The magazine tube extension should lock into the barrel's support band. There should be a ball detent on the front (facing toward the muzzle) of the barrel band that engages a series of tooths (like a gear's teeth) that are inside the collar of the Remington magazine tube extensions that screws onto the threads of the original magazine tube. That can be tightened up by turning it, or possibly using Locktite (I think my Remington 1187 has the locking collar Locktited to the original tube).

2. The bayonet mount/mag tube bracket has three holes drilled into the two halves that allow the mount/bracket to be tightened on the barrel and mag extension tube. The middle hole should be drilled slightly lower on the factory Remington and Scattergun Tech mount/bracket. That middle hole allows the screw that runs through it to lock into the annular groove that is on the Remington factory mag extension tubes, and when tightened up will give support to the magazine extension tube from the barrel (see the pic you initially posted).
The two stripped brackets that I have have the middle hole drilled in line with the other two, and thus does not lock into the grooves of the magazine extension tube. Perhaps your mount/bracket has the same layout of holes drilled in it as mine.
By the way, does your bayonet mount/mag tube extension bracket have the front rifle sight brazed onto the upper half, or is there a cutout to accomodate it? And where did you find a heat shield with a cut out to accomodate the rear rifle sight base? And how long would a heat shield need to be to reach the rear of the bayonet wount (if you planned on attaching the heat shield to the mount)?
I'm asking because Gun Parts Corp has had a universal ventilated heat shield originally for military shotguns that has an overall length of 15" (and is also in the white) for about $12.95 and has the catalog/order number of DRA10 (on p.169 of the 21st edition catalog).

If you look closer at the pic, the front blade sight is actually part of the Remington factory smoothbore deer barrel, just like the rear iron sights. The bayonet lug/magazine extension is the one with the annular groove for the offset middle screw of the bracket, and a matching screw. But on my example, there is no upper part to the bracket/bayo lug/sling swivel to attach to the barrel, so it just free floats, there is NO attachment to the barrel anywhere. There are, however, still two free holes in the front and rear ends of the bracket, and I think I will just fabricate a steel band that wraps around the barrel and bolts to the rear hole like a clamp, then parkerize it to match. The heatshield was a metal one I beadblasted, milled out the rectangular cutout for the rear sight, and parkerized. And yes, it comes in handy, especially during three gun matches, that barrel gets HOT!

Aha! I'm afraid that with the low light level and the nonreflective surfase of the 870, I completely missed the absent upper half of the mount and assumed it was there! I am somewhat surprised that someone was selling only half of the assembly.
Constructing a copy of the upper half appears to be a relatively simple process that wouldn't take too long and would involve bending a plate 180 degrees on the ends, drilling/tapping three holes to correspond with the ones on the lower half of the mount/bracket, drilling/cutting out a section on top to allow it to accomodate the front sight, and then bending it along a rod or blank the same diameter as the 870 barrel, as well as beadblasting and parkerizing and finding suitable screws for the assembly. I can offer you a sketch of the upper mount/bracket for more insights on its construction or other assistance.
A couple more questions on your 870:
1. Where did you get the synthetic furniture? The fore end looks like an exact copy of the original 870 Mk.I except that its not walnut.
2. Do you have removable chokes on your 20" barrel? In the picture you posted the barrel looks longer than a 20" barrel with the Remington factory magazine extension (the stepped portion of the extension tends to extend past the muzzle of the 20" barrel about 3/4").
I know the original Mk.Is had a 21" barrel, which is impossible to find, and I am thinking of buying a Mossberg made 24" Rem 870 barrel, having it cut down to 21", and having a flush improved cylinder choke (the type used on the Mk.I) installed and the front sight attached to the upper half of the mount/bracket, though I am having second thoughts on that since removing and reattaching the bracket/mount would likely affect the front sight's alignment.
Is there any help that I can offer you?

Yes, that sketch of the upper would probably clear out my fuzzy train of thought, I had simply planned on making a band to go over the barrel and bolt to the lower bracket.

The synthetic furniture came from Gander Mountain, and is a Speedfeed synthetic with Monte Carlo comb, it lines up perfectly with the rifle sights on the barrel when the shotgun is shouldered. I will probably replace the front blade and rear "V" with the tritium replacements from Meprolight or Trijicon.

It's a 20" factory smoothbore deer barrel, with the Remchoke system. I believe Remington still offers them, and they're not too expensive. As shown in the picture, for home defense, I use the Remington Extra Full Turkey choke and 3" Magnum 000 Buck loads, a VERY tight shot group centered where the sights say they're supposed to go, and it stays tight out to 40 yards, so far. After an attempted home invasion robbery in Citrus Heights a couple years ago, I was determined that the next time any invaders tried to come through my front door, no matter what they were wearing or what drug of choice was in their bloodstream, they wouldn't so much as twitch after receiving Beauford's benediction. (My wife named the shotgun, after seeing Walking Tall...) The Turkey choke does stick out an extra inch or so from the end of the barrel, but that didn't bother me when I assembled the gun.

Yes, I would appreciate any and all help I can get in putting the finishing touches on the old girl, or locating an upper half of the bracket to mate with my lower half. Otherwise I will just have to fabricate what I can.

It's also fun to put in the other chokes, and go shoot skeet against the Perazzi, Red Label, and Superposed folks, heehee! The look on their faces is priceless!

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